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The short answer is "no". A 100A panel will be protected by a 100A or smaller main circuit breaker or fuse, and if the sum of all the loads on the various branches exceeds the main breaker rating, it will trip and power will be disconnected long before any damage can occur to the panel.

for USA, Canada and countries running a 60 Hz power supply service. The short answer is that safe capacity in buildings is determined by a load calculation, not by adding up the nominal ratings of breakers. A quick check for signs of overload would be to check the temperature of your 100A main breaker. Use a $50 non-contact thermometer from a hardware or home improvement store and look for the main to be significantly hotter than the average of other breakers -- over 100F or more than 5-10F hotter than other breakers could be cause for concern.

On a 100A-rated electrical service, you have 19,200 W of continuous power capacity to stay within the 80% of rating load limit indicated by National Electric Code. You can calculate about 3W per square foot of living space for convenience receptacles and lighting, and you should also subtract the wattage of each piece of permanently-installed equipment (such as a garage door opener, electric range, 240V water heater, etc.).

Just like any resource, anything could be abused. You typically do not use all of your electrical circuits at the same time. A 100A panel will usually also be the equipment for disconnecting from the utility service, and have a MAIN BREAKER service-disconnect that will trip (eventually) when you have exceeded safe home capacity. Each individual 15 or 20 amp circuit could also have an 'overload' plugged into them. Just as long as you don't turn on every device at the same time, the smaller circuit breakers won't blow and everything is fine. <><><> Clarification: A 100 amp electrical panel is so called because it is rated at 100 amps. The main breaker or fuse is intended to disconnect power if the load exceeds 100 amps on either of the 2 "legs" of the service. The load on the panel is not the cumulative RATING of the nameplate current limits of the individual breakers in the panel. It is the actual load on the breakers that adds up to the load. A 15 amp breaker is rated at fifteen amps, so that it will shut off if the current goes ABOVE 15 amps. This is to protect the circuit conductors from damage. You could have 20 circuits with 15 amp breakers on each one and only have a load of 5 amps on the whole panel [not 300]! Remember there is no current if there is no load [load allows current]! Do you get a speeding ticket because your speedometer goes up to 120 mph if you are going 25?

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

If you do this work yourself, always turn off the power at the breaker box/fuse panel BEFORE you attempt to do any work AND always use an electrician's test meter having metal-tipped probes (not a simple proximity voltage indicator) to insure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB SAFELY AND COMPETENTLY REFER THIS WORK TO QUALIFIED PROFESSIONALS.

YES. By duplex breaker, you mean 'tandem breaker', a special breaker designed to allow you to get more circuits into a panel that is full or almost full. You most likely… have a 'CTL' type panel in your home. You MUST use 'CTL' breakers, or CTL tandem breakers in that panel. By design, if you look at the bus bars that your breakers snap onto, the upper 60 percent or so is different than the lower 40 percent. The lower bus bars are designed differently so that you cannot install tandem breakers in a certain number of spaces. This prevents you from overloading the panel. Most people at Lowe's and Home Depot do not know this and will give you anything to put into your panel. DON'T! If the CTL tandem doesn't fit, it's not supposed to. Do NOT go back to the store to get a different breaker because that one didn't fit. Call an electrician to install a larger service and panel with more capacity. Installing non-CTL breakers to cirvumvent the safety feature can cause your house to burn down. It costs more to rebuild your home due to electrical fire, than it would have cost to have the job done right by a professional electrician. The above answer is correct, but I would like to add there are some States that do not allow tandem breakers.

Answer Please be more specific....simply replacing the breaker with a 20 amp may cause a fire; if the cable is sized for 15 amp and is overloaded. Answer … Your 15 amp breaker is probably feeding #14 wire. The use of a 20 amp breaker requires at least a #12 wire be used. Fire hazard if breakers and wiring are not sized correctly.

DO NOT FOLLOW THE INSTRUCTIONS BELOW! According to this logic, one could chain an infinite number or sub-panels off of a single one hundred amp feed. The second law of thermo…dynamics prevents this. An hundred amp service is not capable of powering another hundred amp service unless you are trying to move your panel and all of the circuits it feeds as well, without adding another hundred amp load. NEC (National Electrcial Code NFPA Book 72) states that certain loads can be derated but not to this extent. As far as the voltage drop is concerned, you need only worry about this with runs of about two hundred and twenty five feet or more for a 200 Amp Service running 2/0 2/0 4/0 URD direct burial aluminum. What you need is a new 200 Amp service to feed your original 100A panel and another hundred amps to feed your new load. for USA, Canada and countries running a 60 Hertz supply service. Yes you can as long as the feeder to the other 100 amp panel is equal to the ampacity of the breaker. In this case you would need to use a #3 wire rated at 90 degrees C if the distance to the other panel is under 50 feet. If the distance is longer that this a voltage drop calculation would have to be added to increase the wire size. My experience would lead me to believe that you could not install a breaker that was greater to or equal to the rating of the main breaker. To add a sub-panel, you will need to install a breaker that is half or lower than the main breaker. In your case, you have a 100A service; you will need to install a 50A or smaller breaker to service the sub panel. Consult an electrician if in doubt. If you have any doubts about an answer that you get, check the answerer's bio by clicking on their name to check their qualifications. Before you do any work yourself, on electrical circuits, equipment or appliances, always use a test meter to ensure the circuit is, in fact, de-energized IF YOU ARE NOT REALLY SURE YOU CAN DO THIS JOB SAFELY AND COMPETENTLY REFER THIS WORK TO QUALIFIED PROFESSIONALS.

Answer for USA, Canada and countries running a 60 Hz supply service.Lights Lights and outlets are normally wired on separate branch circuits, which means that the lights will… be protected by a separate circuit breaker to the one which protects the outlets. Asking how many lights can go on a branch circuit is like asking "How long is a piece of string?". It is impossible to give a general answer because the total number of lights that can be installed will depend on the wattage and amperage drawn by each light and on whether or not they will all be switched on together at the same times of day or night. If you cannot work out the total amperage of the lights you want to use at any time, compared to the safe load current of the circuit breaker on your lighting circuit, the best advice anyone should give you is to call a licensed electrician for advice. Outlets The number of outlets on a 15 or 20 amp circuit depends entirely on what you will plugging into those outlets. If you are plugging in an appliance that will pull 10 amps then you cannot also plug in another one taking 15 amps! Many different combinations are possible, for example a 15 amp circuit may have 15 outlets but only 2 are being used at any one time, such as a floor lamp and a TV. Generally speaking, most homes have 8 to 10 outlets per a 15 amp circuit. Not all outlets are used at the same time, a lamp here, a TV there, not too much. Regarding lights, you need to add up all the amps pulled by all fixtures on that circuit. The total amps pulled should not exceed 80% of the circuit breaker's maximum amperage. There is an allowance of 1800 watts per outlet for 15 Ampere 120 volt convenience outlets ans 2400 watts per outlet for 20 Ampere outlets. It is required that a continuous load [operating over 4 hours] be served such that the circuit is not loaded past 80% of its capacity, which would allow a continuous 16 amp load on a 20 amp circuit. If there were 2 loads planned, the combined continuous load could not exceed 16 amps between both devices. See NEC [NFPA 70, 2005 edition - National Electrical Code (c)] Article 210, sections 210.20, 210.21 and 210.23. The NEC does not specify a maximum number of outlets per circuit. As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed. Before you do any work yourself, on electrical circuits, equipment or appliances, always use a test meter to ensure the circuit is, in fact, de-energized. IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB SAFELY AND COMPETENTLY REFER THIS WORK TO QUALIFIED PROFESSIONALS

Answer for USA, Canada and countries running a 60 Hz power supply service. No offense, but usually the people who ask this question don't know enough to do it safely. Y…our best bet is to hire a competent electrician. I know they cost money, but that's because they get the job done safely (or they should). That being said, if you would like to attempt this yourself, you should get yourself 2 references: National Electrical Code (whichever revision is in use in your locality, check with the office in your city that issues building permits)- This is essential to do any electrical work safely and properly, and you're going to want to do that. In most cases when installing an electrical panel, the power company will not connect (or reconnect) power to your new panel unless it has been approved by a local electrical inspector. Code Check Electrical- This handy guide is excellent for those unfamiliar with electrical work. It will specifically highlight commonly missed requirements for a code compliant installation. These are for sale at your local Home Depot or large bookstore. Whatever you do, when installing feeders from the meter base to the panel, do it properly by contacting the power company to disconnect your service. Too many do it yourselfers and even electricians have decided to install panel feeders by simply pulling out the meter to disconnect power. This will only disconnect power to one side of the meter. If the live side shorts, it will cause a fire and burn the power company's lines clean through. Please be safe and coordinate your panel installation with the local building authority and power company. As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed. Before you do any work yourself, on electrical circuits, equipment or appliances, always use a test meter to ensure the circuit is, in fact, de-energized. IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB SAFELY AND COMPETENTLY REFER THIS WORK TO QUALIFIED PROFESSIONALS.

ANSWER The amperage that can be used from a service distribution panel is governed by the amperage of the main breaker. If the main breaker is 200 amps then up to a maximum o…f 200 amps can be taken from the panel before the main breaker trips on an over current fault. ANSWER Breaker panels come in a variety of sizes. The current capacity of the breaker panel and its main breaker are governed by the current capacity of the service wiring provided by the electrical supply company. 50 years ago, 60 ampere service was common. Now the smallest common household service in North America is 100 amperes. It is becoming more common to install 150 or 200 ampere service, especially in upscale homes One "planning ahead" approach is to get 100 ampere service, but install a 200 ampere breaker panel with a 100 ampere main breaker. That way, if you ever upgraded to 200 ampere service, you'd already have the correct panel and wiring, and all you'd have to do is take out the smaller main breaker and replace it with a 200 ampere unit For business installations, main breaker panels can be considerably larger. For example, consider a typical roadside hotel (50-75 rooms) or small apartment building (15-20 apartments) with HVAC (individual electrical heat and air conditioning units ). You can think of it as a gigantic house, everything that's in your house but on a larger scale. A 1600 ampere 3-phase main breaker would probably be used, with a distribution panel providing 200 ampere single phase breakers to feed power to 200 ampere subpanels throughout the building. Please read discussion page about the statement in bold print above.

Building codes will vary. In the US, the National Electrical Code (NFPA 70) is the basis for most of those. The answer will vary depending on what the structure is. For a sing…le family home, there is no specific number of outlets per breaker. For commercial work, there is a limit of 10 outlets per 15 amp, and 13 outlets per 20 amp. The actual current draw MUST be taken into account as a practical matter. YOUR local building codes may differ from the NEC.

That's why breaker panels are provided with knock-out blanks. You only remove the blanks that you need. If you have removed too many of the blanks, install unused breakers i…n the empty spaces. Your local hardware store sells breaker knockout blanks or plugs so you do not have to install unused breakers. They are simply plastic spacers that snap into your breaker cover (called a dead front) to keep energized parts from being too easily available for contact. -- Sparkfighter

Yes. But the NEC requires that your first disconnect be installed as close as practical to where the service enters the building. So if the bedroom isn't where the service en…ters the home, you will have to install a stand-alone disconnect where it does and then wire to your panel.

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In the early 60's I was an Electrical Generation Systems Technician in the RCAF. On release in 1966 I started an electrical apprenticeship and received my journeyman's papers in 1969. In 1972 I started my own electrical company, wrote and passed my exams for an A class electrical contractor licence… (MORE)